Can you explain about the formation of cell aggregates with microcarriers, have you seen this and do you have any advice on how to limit this?

Answer

The formation of multiple microcarrier and cell aggregates is a common phenomenon seen for many, if not all, microcarriers under certain conditions. This is driven by cell adhesion molecules (CAMs) that are typically expressed as a consequence of growth and allow cells to adhere to extracellular matrix or other cells. As such, the extent of multi-bead aggregates relates to the amount of turbulent shear in a mixed environment. Depending on the cell line, increasing the agitation rate 12-24 hours after cell attachment will decrease the likelihood of these aggregates forming; however, the micorenvironment produced by such aggregates may be advantageous depending on your culture needs, like 3D approaches. In that case, agitation can be optimized such that aggregates do not become large enough to form stagnant cores leading to cell necrosis. Live/dead staining and other cell health indicators can be useful to defining optimum aggregate size.